#ifndef THREE_IMPROVED_NOISE_HPP
#define THREE_IMPROVED_NOISE_HPP

#include <three/core/math.hpp>

#include <array>

namespace three {

class ImprovedNoise {
public:

  float noise( float x, float y, float z ) {

    static const std::array<int, 512> p = {

      151,160,137,91,90,15,131,13,201,95,96,53,194,233,7,225,140,36,103,30,69,142,8,99,37,240,21,10,
      23,190,6,148,247,120,234,75,0,26,197,62,94,252,219,203,117,35,11,32,57,177,33,88,237,149,56,87,
      174,20,125,136,171,168,68,175,74,165,71,134,139,48,27,166,77,146,158,231,83,111,229,122,60,211,
      133,230,220,105,92,41,55,46,245,40,244,102,143,54,65,25,63,161,1,216,80,73,209,76,132,187,208,
      89,18,169,200,196,135,130,116,188,159,86,164,100,109,198,173,186,3,64,52,217,226,250,124,123,5,
      202,38,147,118,126,255,82,85,212,207,206,59,227,47,16,58,17,182,189,28,42,223,183,170,213,119,
      248,152,2,44,154,163,70,221,153,101,155,167,43,172,9,129,22,39,253,19,98,108,110,79,113,224,232,
      178,185,112,104,218,246,97,228,251,34,242,193,238,210,144,12,191,179,162,241,81,51,145,235,249,
      14,239,107,49,192,214,31,181,199,106,157,184,84,204,176,115,121,50,45,127,4,150,254,138,236,205,
      93,222,114,67,29,24,72,243,141,128,195,78,66,215,61,156,180,

      151,160,137,91,90,15,131,13,201,95,96,53,194,233,7,225,140,36,103,30,69,142,8,99,37,240,21,10,
      23,190,6,148,247,120,234,75,0,26,197,62,94,252,219,203,117,35,11,32,57,177,33,88,237,149,56,87,
      174,20,125,136,171,168,68,175,74,165,71,134,139,48,27,166,77,146,158,231,83,111,229,122,60,211,
      133,230,220,105,92,41,55,46,245,40,244,102,143,54,65,25,63,161,1,216,80,73,209,76,132,187,208,
      89,18,169,200,196,135,130,116,188,159,86,164,100,109,198,173,186,3,64,52,217,226,250,124,123,5,
      202,38,147,118,126,255,82,85,212,207,206,59,227,47,16,58,17,182,189,28,42,223,183,170,213,119,
      248,152,2,44,154,163,70,221,153,101,155,167,43,172,9,129,22,39,253,19,98,108,110,79,113,224,232,
      178,185,112,104,218,246,97,228,251,34,242,193,238,210,144,12,191,179,162,241,81,51,145,235,249,
      14,239,107,49,192,214,31,181,199,106,157,184,84,204,176,115,121,50,45,127,4,150,254,138,236,205,
      93,222,114,67,29,24,72,243,141,128,195,78,66,215,61,156,180

    };

      auto floorX = Math::floor(x),
           floorY = Math::floor(y),
           floorZ = Math::floor(z);

      auto X = ((int)floorX & 255),
           Y = ((int)floorY & 255),
           Z = ((int)floorZ & 255);

      x -= floorX;
      y -= floorY;
      z -= floorZ;

      auto xMinus1 = x - 1,
           yMinus1 = y - 1,
           zMinus1 = z - 1;

      const auto u = fade( x ),
                 v = fade( y ),
                 w = fade( z );

      const auto A = p[X]+Y,
                AA = p[A]+Z,
                AB = p[A+1]+Z,
                 B = p[X+1]+Y,
                BA = p[B]+Z,
                BB = p[B+1]+Z;

      return lerp(w, lerp(v, lerp(u, grad(p[AA], x, y, z),
                                     grad(p[BA], xMinus1, y, z)),
                             lerp(u, grad(p[AB], x, yMinus1, z),
                                     grad(p[BB], xMinus1, yMinus1, z))),
                     lerp(v, lerp(u, grad(p[AA+1], x, y, zMinus1),
                                     grad(p[BA+1], xMinus1, y, z-1)),
                             lerp(u, grad(p[AB+1], x, yMinus1, zMinus1),
                                     grad(p[BB+1], xMinus1, yMinus1, zMinus1))));

  }

private:

  static float fade( float t ) {
    return t * t * t * (t * (t * 6 - 15) + 10);
  }

  static float lerp( float t, float a, float b ) {
    return a + t * (b - a);
  }

  static float grad( int hash, float x, float y, float z ) {
    auto h = hash & 15;
    auto u = h < 8 ? x : y,
         v = h < 4 ? y : h == 12 || h == 14 ? x : z;
    return ((h&1) == 0 ? u : -u) + ((h&2) == 0 ? v : -v);
  }

};

} // namespace three

#endif // THREE_IMPROVED_NOISE_HPP

